From dc49da32b739aac23af4fe99f0250d0f9d3379d5 Mon Sep 17 00:00:00 2001
From: Davin McCall <davmac@davmac.org>
Date: Mon, 3 Jul 2017 01:12:33 +0100
Subject: [PATCH] (Linux) set dinit as child subreaper.

This allows catching/watching double-forking processes even if we
are not PID 1. Double-fork orphans will be reparented to the
subreaper (i.e. Dinit) rather than PID 1 (init).
---
 src/dinit.cc | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/dinit.cc b/src/dinit.cc
index ffbae7d..460bef0 100644
--- a/src/dinit.cc
+++ b/src/dinit.cc
@@ -12,6 +12,9 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <pwd.h>
+#ifdef __linux__
+#include <sys/prctl.h>
+#endif
 
 #include "dasynq.h"
 #include "service.h"
@@ -219,7 +222,11 @@ int dinit_main(int argc, char **argv)
         if (onefd > 2) close(onefd);
         if (twofd > 2) close(twofd);
     }
-    
+
+#ifdef __linux__
+    prctl(PR_SET_CHILD_SUBREAPER, 1);
+#endif
+
     /* Set up signal handlers etc */
     /* SIG_CHILD is ignored by default: good */
     sigset_t sigwait_set;
@@ -229,7 +236,7 @@ int dinit_main(int argc, char **argv)
     sigaddset(&sigwait_set, SIGTERM);
     if (am_system_init) sigaddset(&sigwait_set, SIGQUIT);
     sigprocmask(SIG_BLOCK, &sigwait_set, NULL);
-    
+
     // Terminal access control signals - we block these so that dinit can't be
     // suspended if it writes to the terminal after some other process has claimed
     // ownership of it.
-- 
2.25.1